The Spurs crossed the Red River with a commanding 2-0 lead, no Serge Ibaka to contend with and the majority of NBA followers labeling them as an indefensible force rolling its way to a likely rematch with Miami.

Oklahoma City's Serge Ibaka (9) blocks San Antonio's Tim Duncan (21) during Game 4 of the Western Conference Finals in the NBA playoffs between the Oklahoma City Thunder and the San Antonio Spurs at Chesapeake Energy Arena in Oklahoma City, Tuesday, May 27, 2014. Photo by Nate Billings, The Oklahoman

Now, San Antonio flies south in a 2-2 deadlock, looking sluggish and overwhelmed by the Thunder athletes, unable to solve the Ibaka riddle and facing legit 2012 flashbacks that seemed far-fetched just 72 hours ago.

Oh, what a difference three days and two games make.

So what happened to turn this thing? Why has the momentum been completely flipped? How did the Spurs suddenly go from unstoppable to uncompetitive?

“That’s a great question,” a confounded Tony Parker said following the Spurs’ 105-92 Game 4 loss on Tuesday night.

And it’s one the Spurs must solve in the coming days, or risk a surprising end to a promising postseason run that remains at risk of being the last of the Tim Duncan era.

To find the answers, San Antonio must confront the problems. And that starts with Ibaka, the biggest tangible difference between the first and second pair of games.

Far more than an emotional lift, the once hobbled Ibaka didn’t even flash a limp on Tuesday, leading a transformative defensive effort that has stonewalled the Spurs attack. San Antonio had 120 paint points the first two games, while the Thunder had just six blocks. The Spurs struggled to find only 76 paint points the past two games, while OKC compiled 18 blocks.

Seven of those came from Ibaka, OKC’s game-changing rim protector who the Spurs kept unsuccessfully challenging at the summit.

“I thought about passing a picture out on the bench so they’d know who Serge was,” Gregg Popovich joked postgame. “Really unwise basketball all of a sudden. Instead of hitting the open people that are out there, we started attacking the rim unwisely.”

MORE FROM NEWSOK

Anthony Slater started on the Thunder beat in the summer of 2013, joining after two years as NewsOK.com's lead sports blogger and web editor. A native Californian, Slater attended Sonoma State for two years before transferring to Oklahoma State in...